Fabrication of High-k/Ge Stacks with High Quality GeO2 Interlayer

Abstract

Successful fabrication process of high-k/Ge with GeO2 interlayer has been proposed. Low temperature oxidation of Ge substrate gave rise to no GeO desorption at GeO2/Ge interface, that maintains the interface property to be good except a large VFB shift. Deposition of component metals of high-k material on the GeO2/Ge structure was effective to improve the VFB shift with low temperature annealing. Therefore, low temperature oxidation annealing of metal on GeO2/Ge structure has been expected to fabricate high-k/GeO2/Ge with good interface property. In case of Al2O3/GeO2/Ge, this prediction has been proved. In case of HfO2/GeO2/Ge, however, during the thermal treatment the Hf metal diffuse into Ge substrate which causes the formation of the hillocks. The good characteristic was obtained by preventing the hillocks being formed.